Numerous factors can be the source of difficulty for a worker attempting to lock or unlock large gates and hatches located on the side, deck, bow or stern of a vessel. These factors include the deformation of the gates or hatches, the effects of applied external stresses and impacts and the freezing of the locks that secure the gates or hatches closed. Any one of these factors or a combination thereof can make it difficult for a worker to properly operate the locks and thus the gates and hatches. The tightening of closed gates constitutes a further problem because the gates are generally large in size and difficult to settle in a correct position. These gates are usually fitted with various kinds of hook mechanisms tightened with screws. Tightening can also be accomplished hydraulically, or by using other forced measures and levers to add to the force. Problems also exist with conventional locking mechanisms because they are unable to withstand the forces applied to them when the gates are guided into their properly closed position.